For CIC cars you do not need to visit the dealer. You used to have to to get the FSC code but Tischer is providing that now (or you can get it from *******).
The way the upgrade works is you start the car. Insert the new media (used to be three DVD's but is now USB media). The car will detect the new data and prompt you to enter the FSC code. Once you enter it the car will begin downloading the data from the USB to the internal hard drive. This can take some time (couple hours at least). You can turn off the car during the download and it will begin where it left off when you start up again. During this process you will not be able to use the navigation.
Hope that clears things up.